Resin in taphole clay provides good extrudability and strength at low temperatures. However, it also contains volatile matter that is lost on heating. The blast furnace taphole is subject to a large thermal gradient, leading to variation in the bonding and structure of the clay along the taphole’s length. This has a critical effect on properties. Effects of this variation in properties on furnace operations are not well understood. A simple laboratory test was devised to simulate the thermal gradient, and assess its effects on taphole clays.
Thermogravimetric tests were also conducted at different heating rates. Results of experiments are compared with the results of plant trials, and with a taphole structure removed from a blast furnace prior to demolition. The laboratory results correlate well with plant data and observations.